Portable electric belt sanding machine



Jan. 14, 1958 wERTH 2,819,565

PORTABLE ELECTRIC BELT SANDING MACHINE Original Filed Jan. 28. 1949 3 Sheets-Sheet 1 INVENTOR. '5)

ya, fidw Jan. 14, 1958 R. G. WERTH 6 PORTABLE ELECTRIC BELT SANDING MACHINE Original Filed Jan. 28, 1949 3 Sheets-Sheet 2 Jan. 14, 1958 R. G. WERTH Y PORTABLE ELECTRIC BELT SANDING MACHINE Original Filed Jan. 28, 1949 s Sheets-Sheet 5 IN V EN TOR.

PORTABLE ELECTRIC BELT SANDING MACHINE Rudolph G. Werth, Baraboo, Wis., assignor to Bernard S. Oren, Chicago, Ill.

3 Claims. (Cl. 51170) My invention relates to portable electric belt sanding machines.

This application is a continuation of my copending application Serial No. 319,104, filed November 6, 1952, which was in turn a continuation of my application Serial No. 73,428, filed January 28, 1949, now abandoned.

One of the objects of my invention is to provide a hand portable belt sanding machine which will enable a motor, motor control and chuck unit (such as might be used for a hand portable electric drill or the like) to be used to drive the sanding machine.

A further object is to provide a two-part sanding machine comprising a unit including a motor, handle, and chuck, and a second unit comprising a detachable shaft to which the chuck may be detachably connected and a sanding machine device driven from said chuck.

A further object is to provide an improved portable electric belt sanding machine for use with a portable electric drill chuck or the like.

A further object of my invention is to provide a portable motor driven sanding machine having a handle rockable with the motor to the desired position of angular adjustment in order to secure the desired pressure and direction of motion on the sander and to maintain the full operating sanding surface of the machine in contact with the work at all times during the forward and backward motion of the hand and arm during the sanding operation.

A further object is to provide an improved belt sanding machine as indicated above having a suitable knob by means of which the workman can bear down on the work, and having a suitable handle rockable with the motor and operable by the right hand of the workman for securing the desired direction of motion of the sander.

A further object of my invention is to provide an improved belt sander having a bowed leaf spring pressure equalizing for equalizing the pressure on the work.

A further object is to provide an improved sander in which different degrees of pressure may be exerted on the work by means of different flexible pads and to enaole the sander to used with either high or low powered electric motors and yet obtain the desired results of like parity.

A further object is to provide an improved bowed leaf spring pressure pad for the belt having means whereby when pressure is exerted, acting to straighten out the downwardly bowed portion of the pad, another portion of the pad will be caused to counter-balance the belt-slackening effect of the straightening out of the pad.

A further object of my invention is to provide an improved belt sanding machine having improved means for tightening the belt.

A further object is to provide a sanding device as indicated above in which the power transmission from the motor driven shaft to the sanding rotor comprises a swivel mounted gear housing with a miter gear rotatable with the shaft and asecond miter gear driven by the first Patented Jan. 14, 1958 gear, thus changing the direction of power while permitting through rocking action the desired position of angular adjustment.

A further object is to provide an improved belt sander having means for preventing slippage between the drive roller and the sanding belt.

Further objects and advantages of the invention will i be apparent from the description and claims.

in the drawings, in which an embodiment of my invention is shown,

Figure 1 is a side elevational view of an improved sanding tool embodying my invention;

Fig. 2 is a fore-andaft vertical section of a part of the tool showing the rollers and sanding belt and the transmission leading from the chuck-driven shaft to the rollers;

Fig. 3 is a plan view of the construction shown in Figure 1;

Fig. 4 is a side elevational view of the construction shown in Fig. 3;

Fig. 5 is a vertical staggered sectional view on the line 5-5 of Fig. 4;

Fig. 6 is a horizontal detail sectional view on the line 66 of Pig. 4;

Fig. 7 is a vertical detail sectional view on the line 7-7 of Fig. 4; and

Fig. 8 is a side elevational view showing one unit of the two-part sander separated and used as a portable electric chuck for a drill or the like.

Referring to the drawings in detail, the construction shown comprises a two-part portable sanding apparatus, one part including a motor 1, a pusher handle 2 for manipulating the motor, and a chuck 3 driven from the motor, and the other part including a pair of spacedapart rollers 4 and 5 having parallel axes, a sanding belt 6 running over said rollers t and 5 and transmission from the chuck 3 to the front roller 4. The first part, including the motor, handle and chuck, may be detached from the other part by loosening the chuck 3, and the first part may then be used as a portable electric drill by securing a drill 6 in the chuck 3 as shown in Fig. 8.

In order to provide a generally uniform yielding pressure of the sanding belt on the Wood or other material being surfaced, a bowed spring metal pressure pad 7 is provided for holding the sanding belt 6 in good working engagement with the material being surfaced. In order to secure the proper tension in the belt 6, a belttightening device is provided comprising a pair of knurled nuts 8 held against axial movement between opposed abutments 9 on the sander frame, and a pair of screwthreaded rods 10 mounted for axial movement in cylindrical recesses lti in the frame or housing 11 and side cover 12, respectively, and having threaded engagement with the nuts 8. Each of these rods 15 has a flattened end 13 which engages a notch 14 in the transversely slidable shaft 15 on which the rear roller 5 is mounted.

This transversely extending shaft 15 has its ends 16 flattened on both sides. One flattened end of the shaft is slidable in a slot 17 in the side of the frame or housing 11, and the other flattened end of the shaft is slidable in a slot 18 in the removable side cover 121 of the frame. This side cover is detachably secured to the frame by means of screws 19 extending through the cover 12 and threaded into bosses 20 on the upper side of the backing plate 21 of the frame. It will be seen that by removing the screws 19 and cover 12, ready access is obtained to the sander belt 6 and spring pressure pad 7 for removal and replacement by lateral movement with respect to the frame or casing Ill. The frame 1 and cover 12 together constitute a mounting carriage on which the sanding belt 6 and associated parts are mounted.

In order to make sure that the belt 6 does not become slackened when downward pressure is exerted on the sander to cause it to properly engage the surface to be sanded, the spring pressure pad 7 is bent so as to provide a fulcrum-engaging portion 22 (Fig. 7) which engages a portion of the backing plate 21 which acts as a fulcrum so that when downward pressure is exerted on the tool, acting to straighten out the downwardly bowed portion 23 of the pressure pad, the rear end 24 of the pressure pad will be caused to move away from the rear end of the backing plate 21, thus counteracting or countel-balancing the belt slackening effect due to the straightening out of the downwardly bulged front portion 23 of the pad.

The chuck-driven spindle or shaft 25 is mounted in a frame or housing 26 which is rockably mounted in pillow blocks 27 on the sander housing If and cover 12, respectively. This enables the workman using the tool 2 to hold the handle in any desired position of angular adjustment about the axis of the transmission shaft 28 in i order to maintain the full operating sanding surface of the machine in contact with the work at all times during the forward and backward motion of the hand and arm during the sanding operation.

The rocking transmission housing 26 is provided with a suitable knob or handle 29 which the workman can hold with the left hand, using the right hand to manipulate the handle 2 of the motor and chuck part of the tool and to control the action of the motor by means of the on and off switch 39 located in convenient position with respect to the handle.

The transmission from the chuck-driven spindle 25 to the front roller 4 comprises a miter gear 31 secured to rotate with the chuck-driven spindle 25, a miter gear 32 meshing with this miter gear 31, the transversely-extending shaft 28 secured to rotate with the miter gear 32, a small spur pinion 33 mounted to rotate with the transversely-extending shaft 28, an idler gear 34 (removed in Fig. but shown in Fig. 4) mounted on a stud 35 extending from the side of the sander frame 11, a spur gear 36 meshing with the idler gear 34, and a transversely-extending shaft 37 with which the front roller 4 is secured to rotate. Suitable bearing bushings 38 are provided for the chuck driven spindle and the two transversely-extending shafts. in order to prevent slippage between the roller 4 and sanding belt 7 a nonslip sleeve 39 of rubber or other suitable material is secured about the front roller.

In tightening or loosening the belt 6, the tool is placed in position so that the workman can have ready simultaneous access to both of the belt adjusting nuts 8 so that by using both hands simultaneously he can turn these nuts so as to tighten or loosen both sides of the belt at the same time, thus insuring equalized tension. Improper tracking of the belt 6 may be corrected by tightening or loosening the belt on one side only. The engagement of the flattened portions 13 of the screwthreaded rods with the notches M- in the roller carrying shaft prevents rotation of the screw-threaded rods. The engagement of the flattened portions 16 of the roller carrying shaft 15 prevents any rotation of this shaft as it slides back and forth in the slots 17 and 13.

In using the sander, after tightening up the belt 6 to the desired degree, the workman will place his left hand on the knob 29 and his right hand on the handle 2, press on the switch lever 3th to start the motor and apply the sander belt 6 to the work, bringing the exposed portion of the sander belt into juxtaposition with respect to the surface to be sanded. He wili move the sander over the work, moving the sander in general in the direction of the grain of wood (if the surface being finished is wood), exerting a pressure not too great to cause the motor to slow down too much, and will continue to move the sander over the surface until the desired finish is obtained. The rockable mounting of the motor 1 and handle 2 greatly facilitates the work of the operator in handling the sander. The provision of the knob 29 greatly facilitates the matter of securing the desired pressure of the sanding belt on the work. Any suitable materials may be used for the various parts. For example, the bushings 38 may be of brass. The frame or housing 11, the housing cover 12, and the rockable transmission housing 26 may be aluminum castings.

Referring to Figs. 2, 4, and 7, it will be seen that as the tool is brought into engagement with the Work to be finished, the weight of the tool and the downward pressure of the operator on the handle 29 will bring the skids 44 and 45 into engagement with the work. This will force the lower run of the belt 6 upwardly with respect to the skids so that the lower work-engaging surface of the belt will lie in a plane substantially parallel to the plane of the work-engaging surfaces of the skids. The sliding engagement between the front end of the spring 7 and the front end of the backing plate 21 facilitates this flattening of the spring. The forward move ment of the belt keeps the hooklike rear end of the spring pressure part 7 in engagement with the rear edge of the backing plate 21.

As previously stated, the rockable mounting of the handle greatly facilitates the work of the operator in handling the sander. If the handle were not rockable with respect to the planar sanding surface, the operator, in manipulating the handle, would be apt to upset the apple cart. The operator would be apt to exert his gripping pressure in such a way as to cause the sanding belt to bear heavier on the front end than on the rear end, or vice versa. He might even lift the front end or the rear end so that it would not beer at all on the surface to be sanded, regardless of his downward pressure on the handle 29. The rockable mounting of the handle also minimizes the physical strain on the operator. In various positions the operator may have to hold the tool in such a position that his arm must be held in an unusual strained position. if, in addition to this, his gripping hand has to be held in a definite position with respect to the sanding surfacer, the strain or tension on the hand or arm is at its maximum. With applicants construction, in which the hand grip is rockable with re spect to the sanding surface, the resultant physical strain is minimized. The skids 44 and 45 prevent excessive downward pressure on the handles 2 and 29 from materially affecting the degree of downward pressure of the sanding belt 6 on the work on which it operates.

The housing 26 is provided with a removable cover 40 secured thereto by cap screws 41. The gears 33, 34 and 36 are enclosed by a removable cover 42 secured to the frame 11 by means of cap screws 43. Cup grease may be placed in the housings ill and 26 for the transmission gears.

While I have described my invention mainly in connection with a sanding tool for cutting, grinding, or surfacing woodwork, it is obvious that in some of its phases it might be embodied in other types of machines; for example, rotary planers, routers, and circular saws, and for use on other types of material such as plastics, metal, etc.

The frame 11 and cover 12 may be provided with parallel skids or shoes 44 and 45, respectively, which extend downwardly below the lower surface of the backing plate 21 for engagement with the surface of the work being sanded, thus preventing the backing 21 from causing the bowed leaf spring 23 to exert a positive pressure on the work being sanded. By the use of leaf springs of different thicknesses for different conditions of use, the spring pressure on the sanding belt 6 when the shoes 44 and 45 are pressed against the surface of the work, may be varied as desired.

In the claims where the expressions surface finishing device and planar finishing surface are used, they are to be understood as exemplified in the drawings by the surface finishing sander belt 6 having a substantially flat planar sander surface in engagement with the work. The expression mounting carriage is to be understood as exemplified in the drawings by the housing 11 and cover 12 on which the sander belt 6 and shoes or skid means 44 and 45 are mounted.

Further modifications will be apparent to those skilled in the art, and it is desired, therefore, that the invention be limited only by the scope of the appended claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

l. A portable power tool comprising a mounting carriage, a tool element mounted thereon, a housing pivotably mounted on said carriage, a handle mounted on said housing, mechanical power-transmitting means rotatably mounted longitudinally in said housing, mechanical powertransmitting means arranged on said carriage for driving said tool element, and means including a shaft coaxial with the pivotal axis of said housing dn'vingly interconnecting said two power transmitting means.

2. A portable power-driven surface-finishing tool comprising a mounting carriage, a surface-finishing device mounted thereon having a substantially planar finishing surface, a housing pivotably mounted on said carriage, a handle mounted on said housing, mechanical power-transmitting means rotatably mounted longitudinally in said on said carriage for driving said surface-finishing device,

and power-transmitting means including a gear and a rotatable shaft coaxial with the pivotal axis of said housing interconnecting said two first-mentioned power-transmitting means.

References Cited in the file of this patent UNITED STATES PATENTS 1,400,774 Seaborn Dec. 20, 1921 2,180,039 Driver Nov. 14, 1939 2,526,976 Smith Oct. 24, 1950 2,621,453 Oren Dec. 16, 1952 2,700,256 Lewis Jan. 25, 1955 

